1. Technology Field
The present invention generally relates to communications modules, such as optical transceiver modules. In particular, embodiments of the present invention relate to an insertable shield for use in optical transceiver modules to reduce the emission of electromagnetic interference therefrom, especially in regions where a shell and enclosure of the transceiver engage one another.
2. The Related Technology
Computing and networking technology have transformed our world. As the amount of information communicated over networks has increased, high speed transmission has become ever more critical. Many high speed data transmission networks rely on optical transceivers and similar devices for facilitating transmission and reception of digital data embodied in the form of optical signals over optical fibers. Optical networks are thus found in a wide variety of high speed applications ranging from modest Local Area Networks (“LANs”) to backbones that define a large portion of the infrastructure of the Internet.
Typically, data transmission in such networks is implemented by way of an optical transmitter (also referred to as an “optoelectronic transducer”), such as a laser or Light Emitting Diode (“LED”). The optoelectronic transducer emits light when current is passed through it, the intensity of the emitted light being a function of the magnitude of the current. Data reception is generally implemented by way of an optical receiver (also referred to as an optoelectronic transducer), an example of which is a photodiode. The optoelectronic transducer receives light and generates a current, the magnitude of the generated current being a function of the intensity of the received light.
Various other components are also employed by the optical transceiver to aid in the control of the optical transmit and receive components, as well as the processing of various data and other signals. For example, the optical transmitter is typically housed in a transmitter optical subassembly (“TOSA”), while the optical receiver is housed in a separate receiver optical subassembly (“ROSA”). The transceiver also typically includes a driver (e.g., referred to as a “laser driver” when used to drive a laser signal) configured to control the operation of the optical transmitter in response to various control inputs and an amplifier (e.g., often referred to as a “post-amplifier”) configured to amplify the channel-attenuated received signal prior to further processing. A controller circuit (hereinafter referred to as the “controller”) controls the operation of the laser driver and post-amplifier.
As optical transmission speed provided by transceivers and other communications modules rises, traditionally insignificant operational hindrances become more pronounced. One hindrance that is increasingly encountered as transmission speeds increase involves electromagnetic interference, or “EMI.” EMI is electrical noise produced by components of the transceiver module that is manifested in the form of electromagnetic waves that are emitted from the transceiver.
Optical transceiver packages, especially those operating at high transmission speeds, are especially susceptible to the emission of EMI. This phenomenon is undesirable because EMI can interfere with the proper operation of other electrical components. In particular, the physical configuration of existing transceiver modules does a poor job of containing EMI—especially as the generating speed of the module increases. Some areas of the optical transceiver module are more susceptible than others in emitting undesired EMI. Examples of such areas include joints between the external enclosure an exposed portions of the transceiver shell.
Therefore, there is a need in the industry for a pluggable module, such as an optoelectronic transceiver module, that is configured so as to minimize the emission of EMI. Preferably, the module configuration could be used in environments having high frequency data signal transmissions. Moreover, the module configuration should include means by which specified areas traditionally susceptible to EMI emission are sufficiently shielded to prevent such emission.